diff --git a/ChangeLog.md b/ChangeLog.md
index 20fc35c3..af7a4965 100644
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -15,6 +15,9 @@ v5.0.2p2
     - Shortened error message patterns to make them more adaptable to minor sentence changes.
   - Multibyte characters in the code and comments have been replaced with ASCII characters #278
   - #279 #280 Deal the Apple unsubscribe notification as an ARF message. Thanks to @mnmallea
+  - Add the following error message patterns returned from Exchange Online #281
+    - 4.4.317, 5.4.317: STARTTLS is required to send mail
+    - 4.4.318, 5.4.318: Connection was closed abruptly (SuspiciousRemoteServerError)
 
 v5.0.2
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